644004149 has 4 divisors (see below), whose sum is σ = 681886764. Its totient is φ = 606121536.

The previous prime is 644004143. The next prime is 644004161. The reversal of 644004149 is 941400446.

644004149 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 333610225 + 310393924 = 18265^2 + 17618^2 .

It is not a de Polignac number, because 644004149 - 2¹² = 644000053 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644004143) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18941282 + ... + 18941315.

It is an arithmetic number, because the mean of its divisors is an integer number (170471691).

Almost surely, 2^644004149 is an apocalyptic number.

It is an amenable number.

644004149 is a deficient number, since it is larger than the sum of its proper divisors (37882615).

644004149 is a wasteful number, since it uses less digits than its factorization.

644004149 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37882614.

The product of its (nonzero) digits is 13824, while the sum is 32.

The square root of 644004149 is about 25377.2368275193. The cubic root of 644004149 is about 863.5673653662.

The spelling of 644004149 in words is "six hundred forty-four million, four thousand, one hundred forty-nine".